1. Field of the Invention
The present invention relates to an optical ferrule and a method of molding the same, and to an optical connector using the same.
2. Descriptions of the Related Arts
As an optical connector for connecting multi-core optical fibers collectively, an optical connector adopting a pin inserting positioning system, which is called an MT type optical connector and which corresponds to an optical ferrule for use in an optical connector, which is used for an F12 type multi-core optical fiber connector according to JIS C 5981, is known as shown in FIGS. 17 and 18, the conventional optical ferrule 1 (hereinafter referred to as a ferrule 1 for use in an optical connector), which is used as such a kind of MT type optical connector, is a plastic molded article taking a rectangular shape, in which an optical fiber insertion opening portion 2, an optical fiber insertion hole 3, a guide pin hole 4 and an adhesive pouring window 5 are formed, and which has a structure with a square-shaped flange portion 7 provided on the opposite side (right side of FIG. 17) to a connector connecting end face 6. A naked optical fiber (not shown) from which a cover is detached is inserted in the optical fiber insertion hole 3, and fixed thereto with adhesive. Note that reference numeral 8 shown in FIG. 17(c) denotes a rubber boot for protecting the mouth of the inserted multi-core optical fiber.
Molding of the ferrule 1 for use in an optical connector is performed by use of transfer molding and injection molding depending on molding resin to be used. In a metal mold, a gate for injecting molten resin is usually located on a side surface 7a of the flange portion 7. The position of the gate is illustrated by reference symbol G in FIG. 18. Accordingly, when the metal mold after molding is opened to take out the ferrule 1 for use in an optical connector that is a molded article and the gate G is simply cut with a gate cutter, the gate G remains as a flash on the side surface 7a of the flange portion 7.
Incidentally, an optical connector (not shown) adopting a plug-adapter-plug system, which corresponds to an F13 type multi-core optical fiber connector according to JIS C 5982, has been known as a so-called an MPO optical connector. In the optical connector, a plug (optical connector) constructed by accommodating the ferrule 1 for use in an optical connector in a housing is connected thereto so as to interpose an adapter therebetween. Since the ferrule 1 for use in an optical connector enters a hollow portion of the housing in using the ferrule 1 for use in an optical connector for this MPO optical connector, the flash remaining in the gate G of the flange portion 7 must be removed. Specifically, in the state where such flash remains, the flash acts as a hitching member, thus making it impossible for the ferrule 1 for use in an optical connector to be inserted in the housing. Alternatively, even though the ferrule 1 for use in an optical connector can be inserted therein, the flash is caught by the inner wall of the housing, and there is the concern that the ferrule 1 for use in an optical connector cannot slide in the housing smoothly owing to friction caused by hitching of the flash on the inner wall of the housing. Since this flash cannot be removed by sandblasting, a step for polishing the flash is provided, and the flash of the gate G is usually removed by polishing the side surface 7a of the flange portion 7. However, polishing of all of the many ferrules 1 for use in an optical connector has been significantly troublesome. Furthermore, a polishing apparatus exclusively used for polishing the optical connector-use ferrule is needed.
Accordingly, the present invention was made to overcome the disadvantages of such conventional optical connector-use ferrules. The object of the present invention is to provide an optical ferrule capable of saving the labor for removing the flash which remains on the gate in resin molding, and of automatically manufacturing a large number of optical connector-use ferrules without requiring much manpower, and a method of molding the same. Another object of the present invention is to provide an optical connector using the optical ferrule.